/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.http.server.reactive;

import io.undertow.server.HttpServerExchange;
import org.apache.commons.logging.Log;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DefaultDataBufferFactory;
import org.springframework.http.HttpLogging;
import org.springframework.http.HttpMethod;
import org.springframework.util.Assert;

import java.io.IOException;
import java.net.URISyntaxException;

/**
 * Adapt {@link HttpHandler} to the Undertow {@link io.undertow.server.HttpHandler}.
 *
 * @author Marek Hawrylczak
 * @author Rossen Stoyanchev
 * @author Arjen Poutsma
 * @since 5.0
 */
public class UndertowHttpHandlerAdapter implements io.undertow.server.HttpHandler {

    private static final Log logger = HttpLogging.forLogName(UndertowHttpHandlerAdapter.class);


    private final HttpHandler httpHandler;

    private DataBufferFactory bufferFactory = new DefaultDataBufferFactory(false);


    public UndertowHttpHandlerAdapter(HttpHandler httpHandler) {
        Assert.notNull(httpHandler, "HttpHandler must not be null");
        this.httpHandler = httpHandler;
    }

    public DataBufferFactory getDataBufferFactory() {
        return this.bufferFactory;
    }

    public void setDataBufferFactory(DataBufferFactory bufferFactory) {
        Assert.notNull(bufferFactory, "DataBufferFactory must not be null");
        this.bufferFactory = bufferFactory;
    }

    @Override
    public void handleRequest(HttpServerExchange exchange) {
        UndertowServerHttpRequest request = null;
        try {
            request = new UndertowServerHttpRequest(exchange, getDataBufferFactory());
        } catch (URISyntaxException ex) {
            if (logger.isWarnEnabled()) {
                logger.debug("Failed to get request URI: " + ex.getMessage());
            }
            exchange.setStatusCode(400);
            return;
        }
        ServerHttpResponse response = new UndertowServerHttpResponse(exchange, getDataBufferFactory(), request);

        if (request.getMethod() == HttpMethod.HEAD) {
            response = new HttpHeadResponseDecorator(response);
        }

        HandlerResultSubscriber resultSubscriber = new HandlerResultSubscriber(exchange, request);
        this.httpHandler.handle(request, response).subscribe(resultSubscriber);
    }


    private class HandlerResultSubscriber implements Subscriber<Void> {

        private final HttpServerExchange exchange;

        private final String logPrefix;


        public HandlerResultSubscriber(HttpServerExchange exchange, UndertowServerHttpRequest request) {
            this.exchange = exchange;
            this.logPrefix = request.getLogPrefix();
        }

        @Override
        public void onSubscribe(Subscription subscription) {
            subscription.request(Long.MAX_VALUE);
        }

        @Override
        public void onNext(Void aVoid) {
            // no-op
        }

        @Override
        public void onError(Throwable ex) {
            logger.trace(this.logPrefix + "Failed to complete: " + ex.getMessage());
            if (this.exchange.isResponseStarted()) {
                try {
                    logger.debug(this.logPrefix + "Closing connection");
                    this.exchange.getConnection().close();
                } catch (IOException ex2) {
                    // ignore
                }
            } else {
                logger.debug(this.logPrefix + "Setting HttpServerExchange status to 500 Server Error");
                this.exchange.setStatusCode(500);
                this.exchange.endExchange();
            }
        }

        @Override
        public void onComplete() {
            logger.trace(this.logPrefix + "Handling completed");
            this.exchange.endExchange();
        }
    }

}
